21386836 has 6 divisors (see below), whose sum is σ = 37426970. Its totient is φ = 10693416.

The previous prime is 21386821. The next prime is 21386857. The reversal of 21386836 is 63868312.

It can be written as a sum of positive squares in only one way, i.e., 21344400 + 42436 = 4620^2 + 206^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21386795 and 21386804.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2673351 + ... + 2673358.

Almost surely, 2^21386836 is an apocalyptic number.

It is an amenable number.

21386836 is a deficient number, since it is larger than the sum of its proper divisors (16040134).

21386836 is a wasteful number, since it uses less digits than its factorization.

21386836 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5346713 (or 5346711 counting only the distinct ones).

The product of its digits is 41472, while the sum is 37.

The square root of 21386836 is about 4624.5903602373. The cubic root of 21386836 is about 277.5761704167.

It can be divided in two parts, 21386 and 836, that added together give a palindrome (22222).

The spelling of 21386836 in words is "twenty-one million, three hundred eighty-six thousand, eight hundred thirty-six".